1. Field of the Invention
In one of its aspects, the present invention relates to a foam pad, preferably a foam pad for use in a vehicular seat. In another of its aspects, the present invention provides a process for producing such a foam pad.
2. Description of the Prior Art
Attachment of a trim cover to a resilient device is generally known.
In most cases, the resilient device is a foam device, although, in some cases, a fibrous matrix such as rubberized horsehair and the like is still being employed. Typically, it is desired to secure a trim cover to a resilient device to produce a vehicular seat or a component of a vehicular seat.
There are three general categories of approaches in attachment of a trim cover to a resilient device: adhesive, foam-in-place and mechanical. The present invention relates to an improvement falling in the latter category and thus, prior art in this category will be discussed.
In the mechanical approach for attachment of a trim cover to a resilient device, there are (at least) four sub-categories. For ease of description, reference will be made to a foam device.
First, it is known in art to employ so-called “hog-rings” to secure a trim cover to a resilient device. In this approach, a metal wire is molded into the so-called A-surface of the foam device. The metal wire is exposed at selected spots, typically in a trench, on the surface of the foam device. A trim cover is provided and has a finished outer surface made of leather, cloth, vinyl or the like. Commonly attached to the underside of the trim cover is a non-woven material, a felt material and the like. A hard plastic (or other) bead is attached to the non-woven material. Of course other methods of attaching the hard plastic bead to the trim cover are used in the art. The trim cover is attached to the foam device by aligning the metal wire in the foam device with the hard plastic bead in the trim cover and thereafter engaging the two with a metal ring. Typically, the metal ring is deployed from a so-called hog-ring gun. This approach has been used for many years to secure a trim cover to a foam device. This approach suffers from a number of drawbacks. For example, a significant capital cost is required to acquire the hog-ring gun and a significant associated labor cost is required to ensure that trim covers can be attached to foam devices at a rate commensurate with the rate at which the foam device is being produced. Further, since deployment of the first hog-ring immovably secures the trim cover to foam device, there is no play or give. The result of this is that perfect placement of trim cover over the foam device must be achieved prior to deployment of the first hog ring to avoid significant loss of efficiency. Still further, this approach is difficult to use reliably when producing a vehicular seat product which incorporates one or more of a seat heater and an occupant detection system. Still further, the use of metal in the foam device creates additional cost in recycling the finished product after complete of its life cycle. A modification of this approach is to replace the metal wire typically molded into the A-surface of the foam device with a mounting device made of foam—see, for example, Canada patent application 2,165,930 [Grund et al.], published on Jun. 24, 1996 and DE 44 46 450 C1[Johnson Controls GmbH & Co.], granted Apr. 4, 1996. Another modification of this approach is to utilize a mechanical clip to connect the trim cover to the metal wire molded into the A-surface of the foam device—see, for example DE 195 30 379 C2 [Johnson Controls GmbH & Co.], published Dec. 19, 1996.
Second it is known to utilize a plurality of independent or single mechanical clips to secure the trim cover to the foam device. In this approach, a series of mechanical clips is molded in the A-surface of the foam device. Each mechanical clip typically comprises a base which is molded into the foam and a receptacle or clip portion which emerges from the foam at selected locations on the A-surface of the foam device. See, for example, one or more of the following prior art references:                DE 299 17 372 U1 [Johnson Controls GmBH & Co.], published Feb. 24, 2000; and        DE 298 21 697 U1 [Bertrand Faure Sitztechnik GmbH & Co.], published Mar. 25, 1999.For a typical vehicular seat component (e.g., a seat bottom or a seat back), it is common to require 12-30 of these clips to be molded into the foam device. The current approach of using these clips is to cast a receptacle in the mold. The receptacle receives a clip portion while the base portion remains exposed so that it may be molded into the foam. The reason for using such a receptacle in the mold is that, in the prior art, it was thought to be critical to use such a receptacle to avoid foam fouling of the clip portion. The use of such a receptacle has led to casting a wide platform in the mold into which the receptacle is built. Unfortunately, the resulting foam pad or device contains a trench typically having a width of 20 mm or more. There is an ongoing need to avoid the presence of such wide trenches in foam pad which are utilized in vehicular seat applications.        
Third, it is known to use so-called Velcro™-type fasteners to attach a trim cover to a foam device. These fasteners are also known in the art as touch fasteners or “hook and loop” fasteners. While this approach is reliable, it does suffer from a number of drawbacks. For example, this type of fastener is generally regarded one of the most expensive approaches to utilize to secure a trim cover to a foam device. Further, this approach is not well suited to fastening around a curve portion of the foam device without incurring significant wastage. Third, in many applications, the use of this approach necessitates the use of a wide fastener (20 mm or more) to achieve sufficient pullout strength. There is an ongoing need to avoid the presence of such wide trenches in foam pad which are utilized in vehicular seat applications.
Fourth, from U.S. Pat. No. 5,641,552 [Tillner], it is known to utilize an anchoring strip which is molded in A-surface of the foam device. The anchoring strip is in the form of a wide, flat connecting bar made of a molded plastic body (polypropylene is provided as an example) and having a series of C-clips disposed at various spots along its length. The wide, flat connecting bar is described as being flexible perpendicular to its main plane. It is clear that this is the only moment of flexibility of the wide, flat connecting bar. No information is provided in Tillner on how the anchoring strip is actually mold into the foam part.
Thus, despite the advances made to date, there is still room for improvement. Specifically, it would be advantageous to have a trim cover attachment technique that could be utilized with a foam pad in a manner which obviates or mitigates and least one of the above-mentioned drawbacks of the prior art.